Modified mechanisms for page-based navigation.  Frame will append <script> that points to requested code behind page.  The enclosed type will then be used in the following request to get the visual tree.
Modified stackoverflow demo to work with new code behind mechanism.
Faps can now have code behind files that are included on first request.
Created mechanism for App code behind.
If onComplete callback for js imports wasn't specified, don't crash.
Modified sdb demo to illustrate use of view model.
Added "RootVisual" to App.  Changed the sdb demo app to set the DataContext on the root visual which is more accurate.
Fixed "Nullstone.DoesImplement" so it correctly identifies if a type implements an interface.  Also fixed constructor for PropertyChangedEventArgs.  Modified sdb demo main view model to demonstrate property change notification.
Added auto notify property mechanism to nullstone.
Added ObservableObject that implements INotifyPropertyChanged.
Shortened MainViewModel initialization.
Introduced Nullstone.Namespace to allow nicer syntax for declaring namespaces.
Condensed files using new namespace technique.
Condensed more js code behind files with new namespace technique.
Implemented ButtonBase.Command and ButtonBase.CommandParameter.  Migrated stackoverflow demo to use view models.  Items are not changing when new page is requested.
More fixes to Nullstone.DoesImplement. Was not checking base classes for interface declarations.  Added GetBindingExpression to FrameworkElement.
Ensured race condition wouldn't happen with stackoverflow demo.
Better json parsing when receiving data from AjaxJsonRequest.
Modified demos to utilize MVVM objects that are in Fayde now.
Implemented VirtualizingStackPanel.
(cherry picked from commit b5dac453032342e9682cf0bfdfe297c88f74c786)